Chapter 2 Getting Started with AutoCAD

1
Learning Objectives

• Draw lines using the LINE command and its
  options.
• Understand various coordinate systems used in
  AutoCAD.
• Use the ERASE commands to clear the drawing area.
• Understand the two basic object selection
  methods Window and Crossing options.
• Draw circles using various options of the CIRCLE
  command.

• Use the ZOOM and PAN display commands.
• Set up units using the UNITS command.
• Set up and determine limits for a given drawing.
• Plot drawings using the basic plotting options.
• Use the Options dialog box to specify the
  settings.

2

• DRAWING LINES IN AutoCAD

You can invoke the LINE command by choosing the
Line button in the Draw toolbar, or by choosing
Line from the Draw menu, or by entering LINE at
the Command prompt. Once you have invoked the
LINE command, the next prompt, Specify first
point, requires you to specify the starting point
of the line. You can either select a point using
the pointing device After the first point is
selected, AutoCAD will prompt you to enter the
second point at the Specify next point or
Close/Undo prompt. When you select the second
point of the line, AutoCAD will again display the
prompt Specify next point or Close/Undo. At
this point you may continue to select points or
terminate the LINE command by pressing Enter,
ESC, or the Spacebar.
Invoking the LINE command from the Draw toolbar
Learning Objectives
Invoking the LINE command from the Draw menu
3

• The prompt sequence for the drawing, is as
  follows

Command LINE Specify first point Move the
cursor (mouse) and left-click to specify the
first point. Specify next point or Undo Move
the cursor and left-click to specify the second
point. Specify next point or Undo Specify the
third point. Specify next point or Close/Undo
(Press ENTER to exit the LINE command.)
Drawing lines using LINE command
Learning Objectives
4

• The Continue Option

To draw another line starting from the point
where the previous line ended you can use the
Continue option. The following is the prompt
sequence for the Continue option
Using the Continue option with the Line command
Learning Objectives
5

• The Close Option

The Close option can be used to join the current
point with the initial point of the first line
when two or more lines are drawn in continuation.
The following is the prompt sequence for the
Close option for the figure
Command LINE Specify first point Pick first
point. Specify next point or Undo Pick second
point. Specify next point or Undo Pick third
point. Specify next point or Close/Undo Pick
fourth point. Specify next point or Close/Undo
C (Joins the fourth point with the first point.)
Using the Close option with the LINE command
Learning Objectives
6

• The Undo Option

If you draw a line, and then realize that you
made an error, you can remove the line using the
Undo option. The following example illustrates
the use of the Undo option for the figure
CommandLINE or L (L is command alias of LINE
command) Specify first point Pick first point
(Point 1 in the Figure). Specify next point or
Undo Pick second point (Point 2). Specify next
point or Undo Pick third point. Specify next
point or Close/Undo Pick fourth point. Specify
next point or Close/Undo U
(Removes last line from point 3 to point
4.) Specify next point or Close/Undo U
(Removes next line from point 2 to point
3. Specify next point or Close/Undo
Removing lines using the Undo option of the LINE
command
Learning Objectives
7

• COORDINATE SYSTEMS

To specify a point in a plane, we take two
mutually perpendicular lines as references. The
horizontal line is called the X axis, and the
vertical line is called the Y axis. The point of
intersection of these two axes is called the
origin. The X coordinate measures the horizontal
distance from the origin on the X axis. The Y
coordinate measures the vertical distance from
the origin on the Y axis. The origin has the
coordinate values of X 0, Y 0. The origin is
taken as the reference for locating any point in
the XY plane. This method of specifying points is
called the Cartesian coordinate system.
Cartesian coordinate system
Learning Objectives
8

• TYPES OF COORDINATE SYSTEMS

In AutoCAD, the default origin is located
at the lower left corner of the graphics area of
the screen. AutoCAD uses the following coordinate
systems to locate a point in an XY plane

• Absolute Coordinate System
• Relative Coordinate System
• Direct Distance Entry

Learning Objectives
9

• Absolute Coordinate System

In the absolute coordinate system the points are
located with respect to the origin (0,0). For
example, a point with X 4 and Y 3 is measured
4 units horizontally (displacement along the X
axis) and 3 units vertically (displacement along
the Y axis) from the origin. In AutoCAD, the
absolute coordinates are specified by entering X
and Y coordinates, separated by a comma.
Absolute coordinate system
Learning Objectives
10
Command LINE Specify first point 1,1
(X 1 and Y
1.) Specify next point or Undo 4,1
(X 4 and Y 1.) Specify
next point or Undo 4,3 Specify next point or
Close /Undo 1,3 Specify next point or
Close/Undo 1,1 Specify next point or
Close/Undo
Drawing lines using absolute coordinates
Learning Objectives
Coordinate Systems
11

• Example 1

For figure, enter the absolute coordinates of the
points in the following table. Then draw the
figure using absolute coordinates. Save the
drawing under the name Exam1.dwg.
Point Coordinates Point Coordinates
1 3,1 5 5,2 2 3,6
6 6,3 3 4,6
7 7,3 4 4,2
8 7,1
To draw the figure the prompt sequence is
Command LINE Specify first point 3,1 (Start
point.)
Drawing a figure using absolute coordinates
Learning Objectives
12
Specify next point or Undo 3,6 Specify next
point or Undo 4,6 Specify next point or
Close/Undo 4,2 Specify next point or
Close/Undo 5,2 Specify next point or
close/Undo 6,3 Specify next point or
close/Undo 7,3 Specify next point or
close/Undo 7,1 Specify next point or
close/Undo 3,1 Specify next point or
close/Undo
Save this drawing. Enter SAVE at the Command
prompt and then press ENTER. The Save Drawing As
dialog box is displayed. Enter the name Exam2 in
the File name edit box to replace Drawing1.dwg
and then choose the Save button.
Learning Objectives
Example 1
13

• Exercise 1

For the figure, enter the absolute coordinates of
the points, then use these coordinates to draw
the same figure. The coordinates of Point 1 are
2, 1. Distance between the dotted lines is 1 unit.
Drawing for Exercise 1
Learning Objectives
14

• Relative Coordinate System

There are two types of relative coordinates

• Relative Rectangular Coordinates
• Relative Polar Coordinates

Learning Objectives
Coordinate Systems
15

• Relative Rectangular Coordinates

The following is the prompt sequence to draw a
rectangle with the lower left corner at point
(1,1). The length of the rectangle is 4 units and
the width is 3 units.
Command LINE Specify first point 1,1 (Start
point.) Specify next point or Undo _at_4,0
(Second point DX 4, DY 0.) Specify next
point or Undo _at_0,3 (Third point DX 0, DY
3.) Specify next point or Close/Undo _at_-4,0
(Fourth point DX -4, DY 0.) Specify next
point or close/Undo _at_0,-3 (Start point DX
0, DY -3.) Specify next point or close/Undo
Drawing lines using the relative rectangular
coordinates
Learning Objectives
Relative Coordinate System
16

• Example 2

Draw the figure using relative rectangular
coordinates of the points given in the table that
follows.
Point Coordinates Point Coordinates 1
3,1 8
_at_-1,-1 2 _at_4,0 9
_at_-1,1 3 _at_0,1 10
_at_-1,0 4 _at_-1,0 11
_at_0,-2 5 _at_1,1 12
_at_1,-1 6 _at_0,2 13
_at_-1,0 7 _at_-1,0 14
_at_0,-1
Using relative rectangular coordinates with the
LINE command
Learning Objectives
17
Once you know the coordinates of the points, you
can draw the figure by using AutoCADs LINE
command and entering the coordinates of the
points.
Specify next point or Close/Undo _at_-1,1
Specify next point or Close/Undo _at_-1,0
Specify next point or Close/Undo _at_0,-2
Specify next point or Close/Undo _at_1,-1
Specify next point or Close/Undo _at_-1,0
Specify next point or Close/Undo _at_0,-1
Specify next point or Close/Undo
Command LINE Specify first point 3,1
(Start point.) Specify next point or Undo _at_4,0
Specify next point or Undo _at_0,1 Specify
next point or close/Undo _at_-1,0 Specify next
point or Close/Undo _at_1,1 Specify next point
or Close/Undo _at_0,2 Specify next point or
Close/Undo _at_-1,0 Specify next point or
Close/Undo _at_-1,-1
Learning Objectives
Example 2
18

• Exercise 2

For the figure, enter the relative rectangular
coordinates of the points, then use these
coordinates to draw the figure. The coordinates
of Point 1 are 2, 1.The distance between the
dotted lines is 1 unit.
Drawing for Exercise 2
Learning Objectives
19

• Relative Polar Coordinates

In the relative polar coordinate system, a point
can be located by defining both the distance of
the point from the current point and the angle
that the line between the two points makes with
the positive X axis. The prompt sequence to draw
a line from a point at 1,1 to a point at a
distance of 5 units from the point (1,1), and at
an angle of 30 degrees to the X axis is
Command LINE Specify first point 1,1
Specify next point or Undo _at_5lt30
Drawing a line using relative polar coordinates
Learning Objectives
Relative Coordinate System
20

• Example 3

For the figure, enter the relative polar
coordinates of each point in the table, then
generate the drawing. Use absolute coordinates
for the start point (1.5, 1.75). The dimensions
are shown in the drawing. Also, save this drawing
as Exam3.dwg.
Point Coordinates Point Coordinates 1
1.5,1.75 7
_at_1.0lt180 2 _at_1.0lt90 8
_at_0.5lt270 3 _at_2.0lt0 9
_at_1.0lt0 4 _at_2.0lt30 10
_at_1.25lt270 5 _at_0.75lt0 11
_at_0.75lt180 6 _at_1.25lt-90 12
_at_2.0lt150
Drawing for Example 3
Learning Objectives
21
Once you know the coordinates of the points, you
can generate the drawing by using AutoCADs LINE
command and entering the coordinates of the
points.
Command LINE Specify first point 1.5,1.75
(Start point.) Specify next point or Undo
_at_1lt90 Specify next point or Undo _at_2.0lt0
Specify next point or Close/Undo _at_2lt30
Specify next point or Close/Undo _at_0.75lt0
Specify next point or Close/Undo _at_1.25lt-90
Specify next point or Close/Undo _at_1.0lt180
Specify next point or Close/Undo _at_0.5lt270
Specify next point or Close/Undo _at_1.0lt0
Specify next point or Close/Undo _at_1.25lt270
Specify next point or Close/Undo _at_0.75lt180
Specify next point or Close/Undo _at_2.0lt150
Specify next point or Close/Undo C
(Joins the last point with the first point.)
Save this drawing by entering SAVE at the Command
prompt and then press ENTER. The Save Drawing As
dialog box is displayed. Enter the name Exam3 in
the File name edit box to replace Drawing1.dwg
and then choose the Save button. The drawing will
be saved with the given name in the My Documents
directory.
Learning Objectives
Example 3
22

• Exercise 3

Draw the object as shown in the figure using the
absolute, relative rectangular, and relative
polar coordinate systems to locate the points. Do
not draw the dimensions they are for reference
only.
Drawing for Exercise 3
Learning Objectives
23

• Direct Distance Entry

You can draw a line by specifying the length of
the line and its direction, using the Direct
Distance Entry. The direction is determined by
the position of the cursor, and the length of the
line is entered from the keyboard. If Ortho is
on, you can draw lines along the X or Y axis by
specifying the length of line and positioning the
cursor along ortho direction. You can also use
the direct distance entry with polar tracking and
SNAPANG.
Using the Direct Distance Entry to draw lines
Command LINE Specify first point Start
point. Specify next point or Undo Position the
cursor and then enter distance. Specify next
point or Undo Position the cursor and then
enter distance.
Learning Objectives
Coordinate Systems
24

• Example 4

In this example you will draw the object as shown
in the figure, using direct distance entry. The
starting point is 2,2.
In this example, you will use the polar tracking
option to draw the lines. The default angle that
is specified for polar tracking is 90-degree. As
a result, you can use the polar tracking to draw
lines at an angle that is divisible by 90. This
is the reason, you first need to add another
angle of 45-degree to the polar tracking that
will allow you to track the lines drawn at an
angle divisible by 45.
Drawing for Example 4
Learning Objectives
25
The following is the Command prompt sequence for
drawing the object in the figure
Command LINE Specify first point 2,2 Specify
next point or Close/Undo 2 (Move the
cursor horizontally and enter the length of the
line, 2, from the keyboard.) Specify next point
or Close/Undo .7071 (Select POLAR in the
status bar and position the cursor in a 45-degree
direction and enter .7071.) Specify next point or
Close/Undo 1 Move the cursor up vertically,
then enter 1. Specify next point or Close/Undo
3 Move the cursor left horizontally, then enter
3. Specify next point or Close/Undo 1 Move
the cursor down vertically, then enter 1. Specify
next point or Close/Undo C
Learning Objectives
Example 4
26

• Exercise 4

Use the direct distance entry method to draw a
parallelogram. The base of the parallelogram
equals 4 units, the side equals 2.25 units, and
the angle equals 45 degrees. Draw the same
parallelogram using absolute, relative, and
polar coordinates. Note the differences and the
advantage of using direct distance entry.
Learning Objectives
27

• ERASING OBJECTS

After drawing some objects you may want to erase
some of them from the screen. To erase you can
use AutoCADs ERASE command.
Invoking the ERASE command from the Modify toolbar
The following is the prompt sequence for the
figure shown
Command ERASE Select objects Select first
object. Select objects Select second
object. Select objects
Selecting objects by positioning the pick box at
the top of the object and then pressing the pick
button on the pointing device
Learning Objectives
28

• CANCELING AND UNDOING A COMMAND

If you are in a command and you want to cancel or
get out of that command, press the Esc (Escape)
key on the keyboard.
Command ERASE Select objects Press Esc
(Escape) to cancel the command.
The OOPS command restores objects that have been
accidentally erased by the previous ERASE
command. You can also use the U (Undo) command to
undo the last command.
Command OOPS (Restores erased
objects.) Command U (Undoes the last command.)
Use of the OOPS command
Learning Objectives
29

• OBJECT SELECTION METHODS

One of the ways to select objects is to select
them individually, which can be time consuming if
you have a number of objects to edit. This
problem can be solved by creating a selection set
that enables you to select several objects at a
time. The options available are

• The Window Option
• The Crossing Option

Learning Objectives
30

• The Window Option

This option is used to select an object or group
of objects by enclosing them by a box or window.
The objects to be selected should be completely
enclosed within the window those objects that
lie partially inside the boundaries of the window
are not selected. You can select the Window
option by typing W at the Select objects prompt.
You can also select the Window option by
selecting a blank point on the screen at the
Select objects prompt. This is automatically
taken as the first corner of the window. Dragging
the cursor to the right will display a window.
After selecting all the objects you can specify
the other corner with your pointing device.
Selecting objects using the Window option
Learning Objectives
Object Selection
31

• The Crossing Option

This option is used to select an object or group
of objects by creating a box or window around
them. The objects to be selected should be
touching the window boundaries or completely
enclosed within the window. You can select the
Crossing option by typing C at the Select
objects prompt.
You can also select the Crossing option by
selecting a blank point on the screen at the
Select objects prompt. This is automatically
taken as the first corner of the window. Dragging
the cursor to the left will display a window.
After selecting all the objects you can specify
the other corner with your pointing device.
Selecting objects using the Crossing option
Learning Objectives
Object Selection
32

• DRAWING CIRCLES

To draw a circle you can use the AutoCAD CIRCLE
command. The following is the prompt sequence for
the CIRCLE command
Invoking the CIRCLE command from the Draw toolbar
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr (tan tan radius)
Invoking the CIRCLE command from the Draw menu
Learning Objectives
33

• The Center and Radius Option
• The Center and Diameter Option
• The Two-Point Option
• The Three-Point Option
• The Tangent Tangent Radius Option
• The Tangent, Tangent, Tangent Option

Learning Objectives
34

• The Center and Radius Option

In this option you can draw a circle by defining
the center and the radius of the circle. In this
option, AutoCAD lets you draw the circle by
specifying the center point and the radius of the
circle. For example, if you want to draw a circle
with a center at 3,2 and a radius of 1 unit you
can use the CIRCLE command in the following
sequence
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) 3,2 Specify
radius of circle or Diameterltcurrentgt 1
Drawing a circle using the Center and Radius
option
Learning Objectives
CIRCLE Options
35

• The Center and Diameter Option

In this option you can draw a circle by defining
the center and diameter of the circle. In this
option, AutoCAD lets you draw the circle by
specifying the center point and the diameter of
the circle. For example, if you want to draw a
circle with a center at (2,3) and a diameter of 2
units you can use the CIRCLE command with the
Diameter option in the following sequence
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) 2,3 Specify
radius of circle or Diameterltcurrentgt D
Specify diameter of circle ltcurrentgt 2
Drawing a circle using the Center and Diameter
option
Learning Objectives
CIRCLE Options
36

• The Two-Point Option

You can also draw a circle using the Two-Point
option. In this option AutoCAD lets you draw the
circle by specifying the two endpoints of the
circles diameter. For example, if you want to
draw a circle that passes through the points
(1,1) and (2,1), you can use the CIRCLE command
with 2P option, in the following sequence
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) 2P Specify first
endpoint of circles diameter 1,1 Second
endpoint of circles diameter 2,1 (You
can also use the relative coordinates.)
Drawing a circle using the Two-Point option
Learning Objectives
CIRCLE Options
37

• The Three-Point Option

For drawing a circle, you can also use the
Three-Point option by defining three points on
the circumference of the circle. The three points
may be entered in any order. To draw a circle
that passes through the points 3,3, 3,1 and 4,2,
the prompt sequence is
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) 3P Specify
first point on circle 3,3 Specify second point
on circle 3,1 Specify third point on circle
4,2
Drawing a circle using the Three-Point option
Learning Objectives
CIRCLE Options
38

• The Tangent Tangent Radius Option

A tangent is an object (line, circle, or arc)
that contacts the circumference of a circle at
only one point. In this option AutoCAD uses the
Tangent object snap to locate two tangent points
on the selected objects that are to be tangents
to the circle. Then you have to specify the
radius of the circle. The prompt sequence for
drawing a circle using the Ttr option is
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) T Specify point
on object for first tangent of circle Select
first line, circle, or arc. Specify point on
object for second tangent of circle Select
second line, circle, or arc. Specify radius of
circle ltcurrentgt 0.75
Learning Objectives
39
Drawing a circle using the tangent, tangent,
radius(Ttr) option
Tangent, tangent, radius(Ttr) option
Learning Objectives
40
Tangent, tangent, radius option
Tangent, tangent, radius (Ttr) option
Learning Objectives
CIRCLE Options
41

• The Tangent, Tangent, Tangent Option

This option is a modification of the Three-Point
option. In this option AutoCAD uses the Tangent
osnap to locate three points on three selected
objects to which the circle is drawn tangent. The
following is the prompt sequence for drawing a
circle using the Tan, Tan, Tan option
Command CIRCLE Specify center point for circle
or 3P/2P/Ttr(tan tan radius) Select Tan, Tan,
Tan option from the Draw menu. _ 3P Specify first
point on circle _tan to Select the first
object. Specify second point on circle _tan to
Select the second object. Specify third point on
circle _tan to Select the third object.
Drawing a circle using the Tan, Tan, Tan option
Learning Objectives
CIRCLE Options
42

• Exercise 5

Draw the figure using different options of the
LINE and CIRCLE commands. Use absolute, relative
rectangular, or relative polar coordinates for
drawing the triangle. The vertices of the
triangle will be used as the center of the
circles. The circles can be drawn using the
Center and Radius, Center and Diameter, or Tan,
Tan, Tan option. (Height of triangle 4.5 x sin
60 3.897.) Do not draw the dimensions they are
for reference only.
Drawing for Exercise 5
Learning Objectives
43

• BASIC DISPLAY COMMANDS

Sometimes while drawing, it is very difficult to
see and alter minute details. In AutoCAD, you can
overcome this problem by viewing only a specific
portion of the drawing. This is done using the
ZOOM command. This command lets you enlarge or
reduce the size of the drawing displayed on the
screen. Some of the drawing display commands such
as ZOOM and PAN will be introduced here.

• Zooming the Drawings

• Panning in Realtime

Learning Objectives
44

• Zooming the Drawings

The ZOOM command enlarges or reduces the view of
the drawing on the screen, but it does not affect
the actual size of the entities. After the ZOOM
command has been invoked, different options can
be used to obtain the desired display. The
following is the prompt sequence of the ZOOM
command
Selecting Zoom options from the Standard toolbar
Command ZOOM or Z Specify corner of window,
enter a scale factor (nX or nXP), or
All/Center/Dynamic/Extents/Previous/Scale/Window
ltreal timegt
Invoking the ZOOM command from the View menu
Learning Objectives
45
The various options under ZOOM command are

• Realtime Zooming
• Window Option
• Previous Option
• All Option

Learning Objectives
Basic Display Commands
46

• Realtime Zooming

You can use the Realtime Zoom to zoom in and zoom
out interactively. To zoom in, invoke the
command, then hold the pick button down and move
the cursor up. Similarly, to zoom out, hold the
pick button down and move the cursor down.
Realtime zoom is the default setting for the ZOOM
command. At the Command prompt, pressing ENTER
after invoking the ZOOM command automatically
invokes the realtime zoom.

• Window Option

This is the most commonly used option of the ZOOM
command. It lets you specify the area you want to
zoom in on by letting you specify two opposite
corners of a rectangular window.
Learning Objectives
ZOOM Options
47

• Previous Option

While working on a complex drawing, you may need
to zoom in on a portion of the drawing to edit
some minute details. When you have completed the
editing you may want to return to the previous
view.

• All Option

This option zooms to the drawing limits or the
extents, whichever is greater. Sometimes it is
possible that the objects are drawn beyond the
limits. In such a case the Zoom All option zooms
to fill the drawn objects  in the drawing area
irrespective of its limits.
Learning Objectives
ZOOM Options
48

• Panning in Realtime

You can use the Realtime Pan to pan the drawing
interactively, by sliding the drawing and placing
it at the required position. When you select the
realtime pan, AutoCAD displays an image of a hand
indicating that you are in PAN mode. You can drag
the hand anywhere on the screen to move the
drawing.
Learning Objectives
Basic Display Commands
49

• SETTING UNITS

If you want to change the units while you are
already working on a drawing, the UNITS command
can be used.

• Setting Units Using the Drawing Units Dialog Box

The UNITS command is used to select a format for
the units of distance and angle measurement. You
can invoke this command using the Format menu,
see figure. The UNITS command displays the
Drawing Units dialog box as shown in figure. You
can then specify the precision for the units and
angles from the corresponding Precision drop-down
list, see figure.
Drawing Units dialog box
Invoking the UNITS command from the Format menu
Learning Objectives
Specifying Precision from the Drawing Units
dialog box
50

• Specifying Units

In the Drawing Units dialog box, you can select a
desired format of units from the drop-down list
displayed when you choose the down arrow to the
right of Type edit box. You can select one of the
following five formats
1. Architectural (0'-01/16") 2. Decimal
(0.00) 3. Engineering (0'-0.00") 4. Fractional
(0 1/16) 5. Scientific (0.00E01)
In the following example, the units are set as
decimal, scientific, fractional, and decimal and
fractional to enter the coordinates of different
points
Command LINE Specify from point 1.75,0.75
(Decimal.) Specify next point or
Undo 1.75E01, 3.5E00 (Scientific.) Specify
next point or Undo 10-3/8,8-3/4
(Fractional.) Specify next point or
Close/Undo 0.5,17/4 (Decimal and fractional.)
Learning Objectives
51
If you choose the Engineering or Architectural
format, you can enter the distances or
coordinates in any of the five formats. In the
following example, the units are set as
architectural hence, different formats are used
to enter the coordinates of points
Command LINE Specify first point 1-3/4,3/4
(Fractional.) Specify next point or Undo
11-3/4",3-1/4 (Architectural.) Specify next
point or Undo 010.375,08.75
(Engineering.) Specify next point or
Close/Undo 0.5,4-1/4" (Decimal and
engineering.)
Learning Objectives
52

• Specifying Angle

You can select one of the following five angle
measuring systems
1. Decimal Degrees (0.00) 2.
Deg/min/sec (0d00'00") 3. Grads (0.00g)
4. Radians (0.00r) 5. Surveyors
Units (N 0d00'00" E)
In the following example, the system of angle
measure is Surveyors units and different systems
of angle measure are used to define the angle of
the line
Command LINE Specify first point 3,3
Specify next point or Undo _at_3lt45.5
(Decimal degrees.) Specify next point or Undo
_at_3lt90d3045" (Degrees/min/sec.) Specify next
point or Close/Undo _at_3lt750g
(Grads.) Specify next point or Close/Undo
_at_3ltN45d30E (Surveyors units.)
Specifying angles in Surveyors units
Learning Objectives
53
In AutoCAD, by default the angles are positive if
measured in the counterclockwise direction and
the angles are measured from the positive X axis,
see East. The angles are negative if measured
clockwise.
N, S, E, W directions
Measuring angles counterclockwise from the
positive X axis(default)
Learning Objectives
54
When you choose the Direction button in the
Drawing Units dialog box, the Direction Control
dialog box appears which gives you an option of
selecting the setting for direction of the Base
Angle. If you select the Other option, you can
set your own direction for the Base Angle by
either entering a value in the Angle edit box or
choosing the Pick an Angle button to specify the
angle on the screen.
Setting direction from the Direction Control
dialog box
You can also set the units of measure while
inserting a block from the AutoCAD DesignCenter.
In the Drawing Units dialog box choose any
measuring unit from the When inserting blocks in
this drawing, scale them to drop-down list. Now
while inserting a block from the DesignCenter,
AutoCAD inserts the block with the chosen unit.
Selecting units for inserting the DesignCenter
blocks
Learning Objectives
55

• Example 5

In this example you will set the units for a
drawing according to the following specifications
and then draw the figure.

• Set UNITS to fractional, with the denominator of
  the smallest fraction equal to 32.

• Set the angular measurement to Surveyors units,
  with the number of fractional places for display
  of angles equal to zero.

• Set the direction to 90 degrees (north) and the
  direction of measurement of angles to clockwise
  (angles measured positive in clockwise direction).

Drawing for Example 5
Learning Objectives
56

• Invoke the Drawing Units dialog box by choosing
  Units from the Format menu.

• In the Length area of the dialog box, select
  Fractional from the Type drop-down list. From the
  Precision drop-down list select 0 1/32.

• In the Angle area of the dialog box, select
  Surveyors Units from the Type drop-down list.
  From the Precision drop-down list select N 0d E.
  Also, select the Clockwise check box to set the
  clockwise angle measurement as positive.

Setting units in the Drawing Units dialog box

• Choose the Direction button to display the
  Direction Control dialog box. Select the North
  radio button. Choose the OK button to exit the
  Direction Control dialog box.

• Choose the OK button to exit the Drawing Units
  dialog box.

Example 5
Learning Objectives
57

• With the units set, draw the figure using
  relative polar coordinates. Here the units are
  fractional and the angles are measured from north
  (90-degree axis). Invoke the LINE command and
  specify the points as follows

Command LINE Specify first point 2,2
Specify next point or Undo _at_2.0lt0 Specify
next point or Undo _at_2.0lt60 Specify next
point or Close/Undo _at_1lt180 Specify next
point or Close/Undo _at_1lt90 Specify next point
or Close/Undo _at_1lt180 Specify next point or
Close/Undo _at_2.0lt60 Specify next point or
Close/Undo _at_0.5lt90 Specify next point or
Close/Undo _at_2.0lt180 Specify next point or
Close/Undo C
Angles measured from north (Y axis)
Example 5
Learning Objectives
58

• Forcing Default Angles

When you define the direction by specifying the
angle, the output of the angle depends on the
following

• Angular units
• Angle direction
• Angle base

For example, if you are using the AutoCAD default
setting, lt70 represents an angle of 70 decimal
degrees from the positive X axis, measured
counterclockwise. The decimal degrees represent
angular units, the X axis represents the angle
base, and the counterclockwise represents the
angle direction. AutoCAD lets you bypass the
current settings by entering ltlt or ltltlt before the
angle.
Default angular units, direction, and base
Learning Objectives
59
Assume, for example, that you have changed the
current settings and made the system of angle
measure radians with two places of precision
angle base north (the Y axis), and the direction
clockwise. Now, if you enter lt1.04 or lt1.04r, all
the current settings will be taken into
consideration and you will get an angle of 1.04
radians, measured in a clockwise direction from
the positive Y axis, Figure (a). If you enter
ltlt60, AutoCAD will bypass the current settings
and reference the angle in degrees from the
positive X axis, measuring 60 degrees in a
counterclockwise direction, Figure (b). If you
enter ltltlt1.04r, AutoCAD will use the current
angular units, but will bypass the current angle
base and angle direction. Hence, the angle will
be referenced from the positive X axis, and will
be measured 1.04 radians in a counterclockwise
direction, Figure (c).
Forcing default angles
Learning Objectives
60

• SETTING THE LIMITS OF THE DRAWING

If you want to change the limits while you are
already working in a drawing, the LIMITS command
can be used. When you start AutoCAD, the default
limits are 12.00,9.00. You can use the LIMITS
command to set up new limits. The following is
the prompt sequence of the LIMITS command for
setting the limits of 24,18
Command LIMITS Specify lower left corner or
ON/OFFltcurrentgt 0,0 Specify upper right
corner ltcurrentgt 24,18
Choosing Drawing Limits from the Format menu
Learning Objectives
61

• Setting Limits

Draw a rough sketch of the drawing to calculate
the area needed. For example, if an object has a
front view size of 5 X 5, a side view size of 3 X
5, and a top view size of 5 X 3, the limits
should be set so that they can accommodate the
drawing and everything associated with it. In
figure, the space between the front and side
views is 4 units and between the front and top
views is 3 units. Also, the space between the
border and the drawing is 5 units on the left, 5
units on the right, 3 units at the bottom, and 2
units at the top. Calculate the space you need as
follows. Space along (X axis) 1 5 5 4 3
5 1 24 Space along (Y axis) 1 3 5 3
3 2 1 18 In the case just explained, you
will select a D size (34 X 22) sheet.
Setting limits in a drawing
Learning Objectives
62

• Standard Sheet Sizes

Several standard sheet sizes are available to
plot your drawing. Although in AutoCAD you can
select any work area, it is recommended that you
select the work area on the basis of the sheet
size you will be using to plot the drawing. The
sheet size is the deciding factor for determining
the drawing-related parameters. The following
tables list standard sheet sizes and the
corresponding drawing limits for different scale
factors.

• Standard U.S. Size

Letter Sheet Limits Limits
Limits size size (11) (14)
(1/4"1') A 8.5 x 11 8.5,11
34,44 34',44' B 11 x 17
11,17 44,68
44',68' C 17 x 22 17,22 68,88
68',88' D 22 x 34 22,34
88,136 88',136' E 34 x 44
34,44 136,176 136, 176'
Learning Objectives
63

• International Size

Letter Sheet Limits
Limits size size (11)
(120) A4 210 x 297 210,297
4200,5940 A3 297 x 420 297,420
5940,8400 A2 420 x 594 420,597
8400,11940 A1 594 x 841 595,841
11940,16820 A0 841 x 1189 841,1189
16820,23780
Learning Objectives
64

• Limits For Architectural Drawings

Most architectural drawings are drawn at a scale
of 1/4" 1', 1/8" 1', or 1/16" 1'. You must
set the limits accordingly. The following example
illustrates how to calculate the limits in
architectural drawings
Given
Calculate limits
Sheet size 24 x 18 Scale is 1/4" 1'
Scale is 1/4" 1 or 1/4" 12
or1" 48" X limit 24 x 48 1152"
or 1152 Units 96' Y limit 18 x 48
864" or 864 Units 72'
Thus, the scale factor is 48 and the limits are
1152",864", or 96',72'.
Learning Objectives
65

• Example 6

In this example you will calculate limits and
determine an appropriate drawing scale factor for
the figure. The drawing is to be plotted on a 12"
x 9" sheet.
The scale factor can be calculated as follows
Given or known
Overall length of the drawing 31, Length of
the sheet 12" Approximate space between the
drawing and the edges of the paper 2"
Drawing for Example 6
Learning Objectives
66
Calculate scale factor
A line 31' long will be 31'/4' 7.75" on
paper. Similarly, a line 21' long 21'/4'
5.25". Approximate space between the drawing and
the edges of paper 2" Therefore, total length
of the sheet 7.75 2 2 11.75" Similarly,
total width of the sheet 5.25 2 2 9.25"
Calculate limits
Scale factor 1" 48" or 1" 4' The length of
the sheet is 12" Therefore, X limit 12 x 4'
48' Also, Y limit 9 x 4' 36'
Learning Objectives
Example 6
67

• Limits For Metric Drawings

When the drawing units are metric, you must use
standard metric size sheets or calculate the
limits in millimeters (mm). The following example
illustrates how to calculate the limits for
metric drawings.
Given
Calculate limits
Sheet size 24" x 18" Scale 1 20
Scale is 1 20 Therefore, scale factor 20 X
limit 24 x 25.4 x 20 12192 units Y limits
18 x 25.4 x 20 9144 units
Thus, the limits are 12192 and 9144.
Learning Objectives
68

• Exercise 6

Set the units of the drawing according to the
following specifications and then make the
drawing as shown in the figure (leave a space of
3 to 5 units around the drawing for dimensioning
and title block). The space between the dotted
lines is 1 unit.

• Set UNITS to decimal units, with two digits to
  the right of the decimal point.

• Set the angular measurement to decimal degrees,
  with the number of fractional places for display
  of angles equal to 1.

Drawing for Exercise 6

• Set the direction to 0 degrees (east) and the
  direction of measurement of angles to
  counterclockwise (angles measured positive in a
  counterclockwise direction).

4. Set the limits leaving a space of 3 to 5 units
around the drawing for dimensioning and
title block.
Learning Objectives
69

• INTRODUCTION TO PLOTTING DRAWINGS

Once you have created a drawing in the current
session of AutoCAD, you may need to have its hard
copy. This hard copy is very useful in the
industry and can be created by plotting and
printing it on a sheet of paper. Drawings can be
plotted by using the PLOT command, and AutoCAD
will display the Plot dialog box when you invoke
the PLOT command.

• Basic Plotting

Basic plotting involves selecting the correct
output device (plotter), specifying the area to
plot, selecting paper size, specifying the plot
origin, orientation, and the plot scale.
Invoking the PLOT command from the File menu
Learning Objectives
70

• Example 7

You will plot the drawing as shown in the figure
using the Window option to select the area to
plot. The drawing was drawn in Example 3 of
Chapter 1 and here it is assumed to be open on
the screen. Assume that AutoCAD is configured for
two output devices Default System Printer and HP
LaserJet 2100 Series PS.

• Invoke the Plot dialog box from the Standard
  toolbar, or the File menu (choose Plot), or by
  entering PLOT at the Command prompt.

Drawing for Example 7
Learning Objectives
71

• Choose the Plot Device tab. Under Plotter
  Configuration area the name of the default system
  printer will be displayed (in this example it is
  HP LaserJet 2100 Series PS). You can use any
  other printer by selecting the name of the device.

• Now choose the Plot Settings tab and here, choose
  the Window button in the Plot area. You can
  select the object for plotting by creating a
  window around it on the screen. Now, select the
  first and second corners and specify the plot
  area.

Plot dialog box with the Plot Device tab

• To set the size for the plot, you can select a
  size from the Paper size drop-down list in the
  Paper size and paper units area. Once you select
  a size, you can also select the orientation by
  choosing either the Landscape or Portrait radio
  buttons under the Drawing orientation area.

Learning Objectives
Example 7
Plot dialog box with Plot Settings tab
72

• You can also modify values for Plot offset the
  default values for X and Y are 0. For this
  example you can select the Center the plot check
  box to get the drawing in the center of the
  paper. Similarly, you can enter values for Plot
  scale. Open the Scale drop-down list to display
  the various scale factors. From this list you can
  select a scale factor you want to use.

• You can view the plot on the specified paper size
  before actually plotting it by choosing the
  Preview buttons in the Plot dialog box. AutoCAD
  provides two types of Plot Previews, partial and
  full. Full Preview takes more time than Partial
  Preview because the drawing is regenerated. Once
  regeneration is complete, the preview image is
  displayed on the screen,. Here, in place of the
  cursor, a realtime zoom icon is displayed. You
  can hold the pick button of your pointing device
  and then move it up to zoom into the preview
  image and move the cursor down to zoom out of the
  preview image.

Partial Plot Preview dialog box
Learning Objectives
Example 7
73

• If the plot preview is satisfactory, you can
  directly plot your drawing by choosing Plot from
  the shortcut menu, which is displayed by
  right-clicking. If you want to make some changes
  in the settings choose Exit in the shortcut menu
  or press the Esc or the Enter key to get back to
  the dialog box. You can choose the OK button in
  the dialog box to plot the drawing.

Full plot preview with the shortcut menu
Learning Objectives
Example 7
74

• Modifying AutoCAD Settings Using the Options
  Dialog Box

You can use the Options dialog box to change the
settings that affect the drawing environment or
the AutoCAD interface. This dialog box is
displayed by choosing Options from the Tools
menu, or by entering OPTIONS at the command
prompt. You can also invoke this command by
choosing Options from the shortcut menu, which is
displayed by right-clicking in the command window
or in the drawing area when no command is active
or no object is selected. You can change the
AutoCAD default settings and customize them to
your requirements using the Options dialog box.
The dialog box contains tabs. It also has the
Current profile name and the Current drawing
name are displayed on the top, above the tabs.
Options in the drawing area shortcut menu
Learning Objectives
75

• The Options Dialog Box Tabs

The dialog box contains nine tabs that display
the sections to change the different environment
aspects which are as follows

• User Preferences
• Drafting
• Selection
• Profiles

• Files
• Display
• Open and Save
• Plotting
• System

Options dialog box (Files tab)
Learning Objectives
76

• Files

This tab stores the directories in which AutoCAD
looks for driver, support, menu, project,
template, and other files. It uses three icons
folder, paper stack, and file cabinet. The folder
icon is for search path, the paper stack icon is
for files, and the file cabinet icon is for a
specific folder. Suppose you want to know the
path of the menu file. You can select the Menu,
Help, and Miscellaneous File Names folder and
then select Menu File icon to display the path.

• Display

This tab controls drawing and window settings
like screen menu display and scroll bar. You can
also change the color of the graphics window
background, layout window background, command
line background and also the color of the command
line text. It also allows you to modify the
Display resolution and Display performance. Here
you can toggle on and off the different layout
elements such as the layout tabs on the screen,
margins, paper background, and so on. You can
also toggle on and off the display performance
such as the pan and zoom with raster images,
apply the solid fills and so on.
Learning Objectives
Options Dialog Box Tabs
77

• Open and Save

This tab controls the parameters related to
opening and saving of files in AutoCAD. You can
specify the file type for saving while using the
SAVEAS command. The various formats are AutoCAD
2000/LT2000 Drawing (.dwg), AutoCAD Drawing
Template(.dwt), AutoCAD 2004 DXF (.dxf),
AutoCAD 2000/LT2000 DXF(.dxf), AutoCAD R12/LT2
DXF (.dxf), and so on.

• Plotting

The Plotting tab controls the parameters related
to the plotting of drawings in AutoCAD. You can
set the Default output device and also add a new
plotter. You can set the general parameters such
as the layout or plot device paper size. It is
possible to select the spool alert for the system
printer and also the OLE plot quality.
Learning Objectives
Options Dialog Box Tabs
78

• System

This tab contains AutoCAD system settings options
such as the 3D graphics display and Pointing
device settings options where you can choose the
pointing device driver. Here you can also set the
different system parameters such as the single
drawing mode instead of MDE, the display of the
Startup option while opening a new session of
AutoCAD and the OLE Properties dialog box, and
beep for wrong user input. You also have options
to set the parameters for database connectivity.

• User Preferences

This tab controls settings that depend on the way
the user prefers working on AutoCAD, such as the
Right-click Customization where you can change
the shortcut menus. You can set the units
parameters for the AutoCAD DesignCenter as well
as the priorities for different data entry
methods. Here it is possible set the order of
object sorting methods and also set the
lineweight options.
Learning Objectives
Options Dialog Box Tabs
79

• Drafting

This tab controls settings such as the Autosnap
Settings and the Aperture Size. Here you can also
set the toggles on and off for the different
Autotracking settings.

• Selection

This tab controls settings related to the methods
of Object Selection such as the Grips which
enables you to change the various grip colors and
the grip size. You can also set the toggles on or
off for the different selection modes.

• Profiles

This tab saves and restores the system settings.
To set the Profile in the Options dialog box,
choose the Profile tab and then choose the Add to
list button. The Add Profile dialog box appears.
Enter the Profile name and description. Then
choose the Apply Close button. Next, make the
new profile current and then specify the
settings. The settings are saved in the new
profile and can be restored anytime by making the
profile current.
Learning Objectives
Options Dialog Box Tabs
80

• Example 4

In the following example you will use the Options
dialog box to create a profile that contains the
specified settings.

• To invoke the Options dialog box, choose Options
  from the Tools menu.

• In the Options dialog box and choose the Profiles
  tab from it.

• Choose the Add to list button to display the Add
  Profile dialog box. Enter the name of the new
  profile (Myprofile1) and a description of the new
  profile, and then choose the Apply and Close
  button to exit.

• Select Myprofile1 profile and then choose the Set
  Current button to make Myprofile1 current.

• Choose the Display tab and then select the
  Display screen menu check box.

Learning Objectives
81

• Now, choose the Colors button to invoke the Color
  options dialog box. Change the color of the
  graphics window background to white Choose the
  Apply Close button to return to the Options
  dialog box. Notice the changes in screen color to
  white.

• Choose the Plotting tab and then select the Add
  or Configure Plotters button to add another
  printer.

• Choose the Drafting tab to change the AutoSnap
  Marker Size to the maximum.

Color Options dialog box with the Options dialog
box

• See the AutoSnap Marker size, draw a line and
  then choose the Osnap button in the status bar.
  Again invoke the LINE command and move the cursor
  on the previously drawn line a marker is
  displayed and the endpoint.

Learning Objectives
Example 4
82

• From the shortcut menu invoke the Options dialog
  box and choose the Profile tab and then select
  the default profile (ltltUnnamed Profilegtgt). Choose
  the Set Current button to load the default
  settings. The screen settings will change as
  specified in the Default profile.

• Choose the Profiles tab and then select the
  default profile (ltltUnnamed Profilegtgt). Choose the
  Set Current button to load the default settings.
  The screen settings will change as specified in
  the default profile.

• Select the Myprofile1 profile and then choose the
  Set Current button to change the settings
  assigned to Myprofile1 profile.

Learning Objectives
Example 4
83

• Exercise 7

Use the following relative rectangular and
absolute coordinate values in the LINE command
to draw the object. Point Coordinates Point Co
ordinates 1 3.0, 3.0 5
_at_3.0,5.0 2 _at_3,0 6
_at_3,0 3 _at_-1.5,3.0 7
_at_-1.5,-3 4 _at_-1.5,-3.0 8
_at_-1.5,3
Learning Objectives
84

• Exercise 8

For the figure, enter the relative rectangular
and relative polar coordinates of the points,
then use these coordinates to draw the figure.
The distance between the dotted lines is 1 unit.
The coordinates of Point 1 are 3, 1.Save this
drawing as Exer7.dwg.
Drawing for Exercise 8

• Exercise 9

For the figure, enter the relative polar
coordinates of the points. Then use these
coordinates to draw the figure. The coordinates
of Point 1 are 1, 1.Do not draw the dimensions.
Learning Objectives
Drawing for Exercise 9
85

• Exercise 10

Draw the figure, using the LINE and CIRCLE
commands. The distance between the dotted lines
is 1.0 units.

• Exercise 11

Drawing for Exercise 10
Draw the following figure, using the LINE command
and the Ttr option of the CIRCLE command.
Learning Objectives
Drawing for Exercise 11
86

• Exercise 12

Set the units for a drawing according to the
following specifications

• Set the UNITS to architectural, with the
  denominator of the smallest fraction equal to 16.

• Set the angular measurement to degrees/minutes/sec
  onds, with the number of fractional places for
  display of angles equal to 0d00'.

• Set the direction to 0 degrees (east) and the
  direction of measurement of angles to
  counterclockwise (angles measured positive in a
  counterclockwise direction).

Drawing for Exercise 12
Based on the figure, determine and set the limits
of the drawing. The scale for this drawing is
1/4" 1'. Leave enough space around the drawing
for dimensioning and title block. (HINT Scale
factor 48 sheet size required is 12 x 9
therefore, the limits are 12 x 48, 9 x 48
576, 432. Use the ZOOM command and then select
the All option to display the new limits.)
Learning Objectives
87

• Exercise 13

Make the drawing as shown in the figure. The
distance between the dotted lines is 10 feet.
Determine the limits for this drawing and use the
Architectural units with 0'-01/32" precision.

• Exercise 14

Drawing for Exercise 13
Make the drawing as shown in the figure. The
distance between the dotted lines is 5 inches.
Determine the limits for this drawing and use the
Fractional units with 1 1/16 precision.
Learning Objectives
Drawing for Exercise 14
88

• Exercise 15

Make the drawing as shown in the figure. The
distance between the dotted lines is 1 unit.
Determine the limits for this drawing and use the
Decimal units with 0.00 precision.

• Exercise 16

Drawing for Exercise 15
Make the drawing as shown in the figure. The
distance between the dotted lines is 10 feet.
Determine the limits for this drawing and use the
Engineering units with 0'0.00" precision.
Learning Objectives
Drawing for Exercise 16
89

• Problem Solving Exercise 1

Draw the object shown in the figure, using the
LINE and CIRCLE commands. In this exercise only
the diameters of the circles are given. To draw
the lines and small circles (Dia 0.6), you need
to find the coordinate points for the lines and
the center points of the circles. For example, if
the center of concentric circles is at 5,3.5,
then the X coordinate of the lower left corner of
the rectangle is 5.0 - 2.4 2.6.
Drawing for Problem Solving Exercise 1
Learning Objectives
90

• Problem Solving Exercise 2

Draw the following figure, using various options
of the CIRCLE and LINE commands. In this exercise
you have to find the coordinate points for
drawing the lines and circles. Also, you need to
determine the best and easiest method to draw the
0.85 diameter circles along the outermost circle.
Drawing for Problem Solving Exercise 2

• Problem Solving Exercise 3

Draw the drawing in the following figure, using
the absolute, relative rectangular, or relative
polar coordinate system. Draw according to the
dimensions shown in the figure, but do not draw
the dimensions.
Learning Objectives
Drawing for Problem Solving Exercise 3